Glass Tape Research Articles

Crystallization of SrB4O7 in a glass tape and its electrical, dielectric, ferroelectric and nonlinear optical properties

This paper presents the results of an investigation of the electrical, dielectric, ferroelectric, and second-order nonlinear optical properties of SrB4O7 synthesized by methods of both solid-state reaction (SSR) and crystallization of a glass tape (GT). To obtain GTs of SrB4O7, the melt consisting of appropriate precursors was rapidly cooled using a twin-roller. The prepared GTs were crystallized at 730°C for different durations and analyzed by X-ray diffraction. The formation of “extended” crystals in the central part of GTs due to the application of the GT technology is discussed. The investigation of the current-voltage characteristic of the sample prepared by SSR showed that its breakdown voltage is higher than 1000 V. The measurements of the dielectric parameters in the frequency range of 1 KHz–1 MHz showed that the dielectric constant is about 7.5, and the dielectric loss varies from 0.002 to 0.0008. These parameters are sufficiently stable in the temperature range from room temperature to 150°C. The ferroelectric properties of the GT crystallized at 730°C for 3 h were also investigated. At 20 kV/cm, a remnant polarization of 0.18 μC/cm2 was measured. Optical measurements showed that the intensity of second-harmonic generation in the GT crystallized at 730°C for 3 h is 5.4 times higher than that of KH2PO4 (KDP).

EVALUATION OF THE CURING KINETICS OF A POLYMER MATRIX COMPOSITE USING A SENSOR CONTAINING AN ELECTRICALLY CONDUCTIVE FILLER

In this work, the kinetics of the curing of fabric GFRP was carried out by measuring the parameters of its electrical conductivity. A compound of epoxy resin (ED-20), plasticizer (DBF) and hardener (PEPA) with the addition of finely milled graphite (FMG) was used as a matrix. To en-sure high-quality mixing of FMG in epoxy resin, a planetary mixer was used. Plain weave glass tape 0.2 mm thick with two woven wires was impregnated with a matrix compound. This tape was placed onto a beam 4 mm thick made of typical GFRP as an external electrically conductive functional sensor (FS). During curing at room temperature, periodic measurements of the electrical conductivity of the FS and the stiffness of the beam with FS in three-point bending were carried out. The amount of FMG into the matrix compound was below the percolation threshold; there-fore, electrical measurements of FS required alternating current. The dependence of the imped-ance on the current frequency (from 10 Hz to 1 MHz) was recorded. Comparison of the change in FS electrical impedance with the change in the beam stiffness during the curing showed their close correlation. The proposed method of measuring the FS impedance can be used to assess the degree of curing of the polymer matrix in critical large-sized composite products during the manufacturing process.

Synthesis of a new compound in the SrO-TiO2-B2O3 system and its dielectric, ferroelectric, nonlinear optical and electrical properties

In this paper, we report on a new compound in the SrO-TiO2-B2O3 system. For the first time, the compound was synthesized by crystallization of glass tapes (GTs) obtained from a melt of 2SrO-2TiO2-B2O3. The crystallization was performed at 670 °C for 96 h. X-ray studies showed that the formed new phase belongs to the hexagonal system. The lattice parameters were calculated as well. It was suggested to attribute the new material to stoichiometric compound Sr3Ti3O6(BO3)2. The dielectric constant, tangent loss, ac and dc conductivities of the material were found to be almost constant in a wide range of temperatures. Investigation of varistor properties showed that the current-voltage nonlinearity coefficient is 2.05. The measurement of the hysteresis loop confirms the ferroelectricity of the material. It is found that the second-harmonic generation intensity of the new material exceeds that of KDP (by a factor of 3.2 for particles in the size range of 100 ÷ 150 μm).

Development and Evaluation of Fire Resistant Railway Signalling Cable

The railway signalling cable is designed for remote control and teletransmission in underground railway networks. It is very critical situation that the railway signalling cable continues to transmit data in the event of a fire. In this study, the fire resistant test performance of railway signalling cable has been developmented and evaluated via experimental research. A standard railway signalling cable generally consists of conductor, insulation, laying-up, wrapping, screen, inner sheath, armour and outher sheath. The mica tape was added as one layer with 30% overlapping to produce desired fire resistant cable. First step, the railway signalling cable produced used only mica tape used, results show that the cable with mica tape is successful at 110 V. Also, it is not bad for the 250V as it seen the test results. After having non satisfied results, glass tape was added additionally over inner sheath (instead of PP tape) for better results for higher voltage values. After redesign of the cable with addition of glass tape over inner sheath, better results were expected but the results were not as good as expected. Only at 250V appropriate results were achieved according to both IEC 60331 – 21 & 60331-2 standard. When we examined the situation, we saw that the cable was flattened a bit after the new-design. Then, the re-production of the new design cable (mica + glass tape) is been planned without any rework process. All results show that the new design railway signalling cable is resistant to fire tests according to IEC 60331-21, IEC 60331-1&2 up to 1000V as shown in the paper.

Synthesis and Nonlinear Electro-Optical Properties of Zn4B6O13

This paper reports the results of the investigation of second order optical nonlinearity, as well as the polarization nonlinear behavior of Zn4B6O13. For experiments samples were prepared by thermal treatment of glass tapes and solid state synthesis. The tapes were obtained by a rapid melt quenching technique. The thermal processes in the glass tapes were investigated by differential thermal analysis. The synthesized materials were studied by X-ray diffraction. For the sample thermally treated at 710°C for 18 h, the remnant polarization up to 0.04 μC/cm2 was measured under an electric field of 49 kV/cm. It was shown that the second harmonic generation intensity of Zn4B6O13 is 1.9 times higher than that of the well-known optical material KH2PO4.

Characterization of tool wear in i-FSW of AISI 316L material joining

The i-FSW performed by using Nichrome coil pre-heating to the specimen dimension 100 × 75 × 2 mm of AISI 316L material to achieve the desire temperature and make successful friction stir welding. The experiment conducted on conventional milling machine by using TWC tool , whereas the pin length is 1.6 mm and pin diameter is 2.8 mm. The range of spindle rotation 600, 800 & 1000 revolution per min with welding speed of 15, 20 & 25 mm/min. The induction coil set inside the base plate and insulated with Fiber Glass Tape. The pre-heating temperature achieved 120°Celsius, which slightly increase the heat affected zone but also reduce the heat stresses inclusion. The additional heat source provide enough heat energy to produce fine grain size and achieve maximum strength of the weld joint. The experimentation has proved that the i-FSW welding of AISI 316L material is successful and pre-heating of specimen reduces the tool wear of 40% in comparison with normal FSW of specimen. The maximum mechanical properties such as UTS achieved 504 N/mm2 with 97% welding efficiency.

Preparation and characterization of sintered bioactive borate glass tape

Non-aqueous tape casting was used to prepare flexible green tapes from borate glass (1393B3) particles. The tapes were sintered at 550, 575, 600 °C: dense tapes were prepared at 600 °C. In-vitro bioactivity in simulated body fluid (SBF) of tapes sintered at different temperatures was evaluated. SEM, FTIR and XRD results showed slow degradation of dense borate glass tape in SBF compared to the non-dense tapes sintered at different temperatures. Formation of HCA (hydroxy carbonated apatite) on sample surfaces was confirmed after 7D in SBF.

Sophisticated Glass Tapes for Fabrication of Composites

Sophisticated Glass Tapes for Fabrication of Composites

Manufacture and electrical characterisation of high voltage insulation for superconducting busbars – (Part 2) application techniques and electrical characteristics

It is planned that the high voltage electrical insulation on the ITER feeder bus bars will consist of interleaved layers of epoxy resin-pre-impregnated glass tapes (‘pre-preg’) and polyimide. The development and characterisation of these materials was detailed in Part 1 of this report [1]. This paper provides details of the techniques adopted to fully insulate the complex shape of the busbars, forming insulation to fit the many changes in section. Additionally and so far as is reasonably practicable, the insulation should be void and wrinkle free around the helium inlet and outlet pipes that protrude from the surface of the current leads.High voltages will be developed during the pulsed operation of some ITER magnets and in a fault condition, voltages are likely to rise even further. It is therefore necessary to ensure that the insulation can reliably withstand high voltages over the estimated 30,000 operational cycles of the ITER device.The selected materials were processed and techniques developed via three stages (a) short length but full section of current lead (so called, mini mock-up), (b) longer lengths of full cross-section current lead and joint (mock-up) and (c) full sized, busbar. Trials on (a) and (b) were carried out at Rockwood Composites in the UK, tested at the ITER Organization in France and the full sized busbar insulated and tested at the Institute of Plasma Physics (ASIPP), Hefei, PR China.Insulation effectiveness was assessed by measuring the insulation resistance (IR), and performing partial discharge and Paschen tests, before and after thermal cycles to 77 K. All of the criteria established by the ITER organization were met.

ЛАБОРАТОРНОЕ ИЗУЧЕНИЕ ПРОЧНОСТИ НА ИЗГИБ АРМИРОВАННОГО БИС-АКРИЛОВОГО МАТЕРИАЛА ДЛЯ ПРОВИЗОРНЫХ ПРОТЕЗОВ

Background. The use of provisional (interim, temporary) restorations has become a routine procedure in modern dentists after the end of the era of brazed-stamped bridges. The use of traditional acrylic plastics does not provide the necessary strength for the long-term functioning of provisional prostheses. Bis-acrylic materials have helped to eliminate some of the problems associated with traditional acrylic materials. However the disadvantage of bis-acryls is that they can break relatively easily when placed in areas of increased stress. The use of provisional prostheses, obtained by casting or CAD/CAM technology, undoubtedly solve problems, however, prosthetics are significantly more expensive. Another known and cheaper way is to harden polymers by reinforcing them. Objectives ― to study, when conducting a mechanical test, the fracture resistance of glass fiber-reinforced bis-acrylic composite beams. Methods. On a universal testing machine (three-point flexural test), 8 groups of samples were studied depending on the material — Re-fine Bright acrylic material (Yamahachi Dental MFG., CO., Japan), or Luxatemp bis-acrylic material (DMG) and Protemp 4 (3M ESPE), and also, the method of reinforcement of Protemp 4 with GlasSpan fiberglass tape (GlasSpan). The fracture strength (F) was calculated in MPa. Statistical differences between groups were determined using T-test. Results. Comparison of the fracture strengths results between the first control group (Protemp 4 bis-acrylic plastic without reinforcement) and other groups (glass tape reinforcement) revealed a significant hardening of Protemp 4 after reinforcement (p <0,05). Conclusions. The use of reinforcing glass tape with a full impregnation with an adhesive and a flowable composite increases the strength of Protemp 4 more than 2 times.

Candle Soot Coating for Latent Fingermark Enhancement on Various Surfaces.

We demonstrate a facile method termed candle soot coating (CSC) for fast developing latent fingermarks (LFMs) on various kinds of surfaces (glass, ceramic, metal, paper and adhesive tape). The CSC method can be considered as simple, fast, and low-cost as well as providing high contrast for LFM visualization in potential forensic applications.

Hydrodynamics and heat and mass transfer during formation of thin metal glass tape

The mathematical model of hydrodynamic and heat transfer processes in a system, which rotates a disk, a metal tape, an environment, is developed. The adequacy of both the mathematical model and the computing algorithm is confirmed by comparison the computing results with the laboratory experiment. It has been shown that increase of the disc’s rotational speed reduces the thickness of the amorphous metal tape.

Manufacture and mechanical characterisation of high voltage insulation for superconducting busbars – (Part 1) Materials selection and development

It is planned that the high voltage electrical insulation on the ITER feeder busbars will consist of interleaved layers of epoxy resin pre-impregnated glass tapes (‘pre-preg’) and polyimide. In addition to its electrical insulation function, the busbar insulation must have adequate mechanical properties to sustain the loads imposed on it during ITER magnet operation. This paper reports an investigation into suitable materials to manufacture the high voltage insulation for the ITER superconducting busbars and pipework. An R&D programme was undertaken in order to identify suitable pre-preg and polyimide materials from a range of suppliers. Pre-preg materials were obtained from 3 suppliers and used with Kapton HN, to make mouldings using the desired insulation architecture. Two main processing routes for pre-pregs have been investigated, namely vacuum bag processing (out of autoclave processing) and processing using a material with a high coefficient of thermal expansion (silicone rubber), to apply the compaction pressure on the insulation. Insulation should have adequate mechanical properties to cope with the stresses induced by the operating environment and a low void content necessary in a high voltage application. The quality of the mouldings was assessed by mechanical testing at 77K and by the measurement of the void content.

Выравнивание стеклянных элементов из оптическогорадиационно-стойкого стекла К-208 для терморегулирующих покрытий космических аппаратов

Currently, space technology as a passive means for ensuring the thermal regime successfully applied optical coating (elements of thermal control coatings) based on ultrathin (thickness 150 µm) elements of optical radiation-resistant glass К208. The article discusses the process of making glass elements for thermal control coatings includes the following stages: - the action of pulling the glass tape block heated to a high temperature plastic state of the glass through a die steel;- dimensional cutting of glass tape, with the assistance of scraborough diamond tool;- process thermal plastic alignment elements, carried out in a furnace by heating to a temperature of plasticity of the glass under load. The process of the extrusion of highly plastic block large dimension leads to difficulties in ensuring flatness of pulling the glass tape. As a rule, the shape of the glass tape has a convex shape.To provide the required deviation from flatness, the technology of thermal plastic deformation under load of the glass elements. The process of alignment of the convex glass elements, the selected temperatures and time of exposure, allows minimal deviation from flatness (up to 10 µm).Measurements of deviations from flatness of the glass elements before and after the alignment process with the help of a profilometer-profilograph 252 "Caliber". The measurement results confirm the effectiveness of the selected technology alignment.The alignment process allows to obtain thin elements of K-208 glass with minimal deviation from flatness, which allows them to apply the elements of thermal control coatings of spacecraft.

Fabrication of ultrafast laser written low-loss waveguides in flexible As₂S₃ chalcogenide glass tape.

As2S3 glass has a unique combination of optical properties, such as wide transparency in the infrared region and a high nonlinear coefficient. Recently, intense research has been conducted to improve photonic devices using thin materials. In this Letter, highly uniform rectangular single-index and 2 dB/m loss step-index optical tapes have been drawn by the crucible technique. Low-loss (<0.15 dB/cm) single-mode waveguides in chalcogenide glass tapes have been fabricated using femtosecond laser writing. Optical backscatter reflectometry has been used to study the origin of the optical losses. A detailed study of the laser writing process in thin glass is also presented to facilitate a repeatable waveguide inscription recipe.

Testing of the fire-proof functionality of cable insulation under fire conditions via insulation resistance measurements

Two different designs for low-fire-hazard cables were tested under conditions similar to those of the fire test specified in IEC 60331-21. In addition to the other standard requirements, an insulation resistance meter was connected directly to the measurement circuit to monitor the actual state of the cable insulation during the fire tests. The suitability of this measurement of the insulation resistance was demonstrated by testing cables with fire barriers made from mica glass tape and from ceramifiable silicone rubber. The results showed that insulation resistance is sensitively affected by the melting of the organic components of insulation, by the decomposition of the fire retardant, by the ignition of the core insulation and by the formation of a silica layer during a fire test. The results also helped to reveal the importance of flame conductivity in performing such tests. The initial observations are supported by thermogravimetry and differential scanning calorimetry, which are beneficial as a first step towards understanding the mechanisms of fire-proof functionality in cables. The suggested procedure can assist in the comparison of the fire-proof functionalities of different cable designs, in the analysis of their failure mechanisms and in cable design optimisation.

Current Leads for the Wendelstein 7-X Superconducting Magnet System

The stellarator fusion experiment Wendelstein 7-X (W7-X) is presently under assembly at the Greifswald branch of the Max Planck Institute for Plasma Physics, Germany. The W7-X superconducting magnet system basically consists of 50 nonplanar and 20 planar coils, including the interconnecting bus bars, and the support structure. The seven electrical circuits with 10 coils each in a series are supplied by 14 current leads (CLs) operating between the cryogenic and ambient temperature environments. A special feature of these feedthroughs is their upside-down orientation to save space in the vicinity of the machine. Basic electrical CL requirements are maximal steady-state currents of 18.2 kA and voltage strengths of 13 kV to ground. A W7-X CL consists of a copper conductor that also acts as a heat exchanger at the warm end side, in its continuation of a high-temperature superconductor part, and at the cold end side of a copper bar with integrated Nb3Sn rods. All components are fully contained within a CL vacuum chamber that is separated from the main W7-X cryostat vacuum. The high-voltage (HV) electrical insulation is built up of a glass tape epoxy resin system. Mechanical support of the CLs is achieved by a warm and cold glass fiber reinforced plastic flange. There are three He cooling circuits: 1) one for the bus bar and contact cooling; 2) one for the cold end of the CL (both at about 5 K); and 3) one for the CLs heat exchanger (entrance temperature about 50 K). After intensive tests of two prototypes, the series production has been established and completed. The CLs were tested at room temperature (HV, helium leaks, instrumentation, etc.) and with electrical currents up to the maximum current at cryogenic temperatures. This paper gives an overview of the basic CL design requirements and layout as well as on the fabrication and acceptance tests. Furthermore, a description of the assembly progress is given.

R&amp;D of Insulating and Vacuum Pressure Impregnation Equipment for PF1 Coil Double Pancakes

The PF1 coil is one of six poloidal field coils of the ITER magnet system. The PF1 coil winding is constructed from eight double pancakes (DPs), which are plane cylindrical solenoids of about \varnothing 9 t0.1nm in size and about 20 ton in weight. The monolithic electrical insulation of the PF1 coil is designed under ITER requirements and consists of the conductor multilayer turn insulation, the interlayer insulation of the pancakes, and the ground insulation of the winding. Vacuum pressure impregnation (VPI) with the epoxy resin provides the insulation strength after high-temperature curing. This paper presents the research and development results concerning insulating and VPI equipment for PF1 coil insulating. It involves the 12-roll insulation device for lapping of polyimide and glass tape layers, the vacuum chamber for double pancake impregnation and curing, and automated devices and heaters for mixing and supply of the resin under necessary vacuum and temperature conditions. All equipment has been successfully tested using DP mock-ups. The biggest one was manufactured as a full-scale DP sector. Following modeling, the standard insulation samples were taken from the mock-up to prove the mechanical properties of the insulation to meet the ITER requirements. The test results are also given in this paper.

Design principles for handmade electrical insulation of superconducting joints in W7-X

The superconducting magnet system of the Wendelstein 7-X (W7-X) experiment consists of 50 non-planar and 20 planar coils, 121 bus bars and 14 current leads. The connection between bus bars, coils and current leads will be provided by 198 joints. The joints have to be insulated manually during the assembly of the machine in constraint positions and a tight environment. In general the insulation is based on glass tapes impregnated with epoxy resin and special G10 insulating pieces embedded in the glass tape insulation. In critical areas Kapton®-foils are embedded in the insulation. All types of insulation were qualified at mock-ups in a 1:1 model of the expected environment in W7-X. The qualification programme comprises thermal cycling between room temperature and 77K and high voltage tests under air, under vacuum and under reduced pressure (Paschen test). The paper describes the main principles used for different types of handmade Paschen-tight insulations in W7-X and the visual and electrical tests during and after assembly.

Paper‐Derived Bioactive Glass Tape

AbstractPorous bioactive glass (BaG) structures were manufactured applying novel preceramic paper process. Preceramic papers were produced for aqueous suspensions loaded with different contents of pulp fiber and BaG filler. Pressure loading was applied in order to increase the packing density in the paper sheets. The paper sheets were sintered at 630 °C for 1 h. The porous glass–ceramic specimens were characterized for density, porosity, composition, microstructure, and mechanical properties. A pronounced volumetric shrinkage was observed, but no surface flaws or inhomogeneous areas were detected. The mechanical strength using the ball on three balls test and elastic modulus of sintered specimens vary between 21 and 33 MPa and 0.30–0.85 GPa, respectively.